Performance evaluation of a displacement ventilation system for improving indoor air quality: a numerical study.

To evaluate the performance of a ventilation system, the local mean age of air has usually been used to estimate how efficiently fresh air is diffused to a desired location. However, this index alone is often not sufficient to assess the local air quality that is also associated with the property of the contaminant source in a ventilated space. Several new indices have been proposed recently, which enable the use of numerical simulation and appear to be appropriate scales for assessing mixing ventilation systems. These scales are implemented in this work to evaluate the performance of a displacement ventilation system in a workshop for improving indoor air quality. CFD techniques are used to investigate the influence of heat and contaminant sources on the local air quality in the occupied zone. The impact of displacement ventilation on indoor air quality is discussed.